1. Field of the Invention
The present invention relates to a data write apparatus for writing data on a magnetic card.
2. Description of the Prior Art
A magnetic head for magnetically recording/reproducing data on/from a magnetic card has the arrangement shown in FIG. 4. Referring to FIG. 4, reference numeral 1 denotes a recording head for recording data; 2, a reproducing head 2 for reproducing data; and 3, a gap formed between magnetic cores 1a and 2a of the recording head 1 and the reproducing head 2. In this case, when a current corresponding to write data is caused to flow into a winding coil 1b of the recording head 1, a magnetic field is generated by the gap 3, and the write data is recorded on a magnetic track of a magnetic card 4 conveyed on the card conveyor path 5.
FIG. 5A shows a conventional data write apparatus, and FIG. 5B shows the arrangement relationship between the recording head and a sensor shown in FIG. 5A. As shown in FIG. 5B, the recording head 1 is arranged in the card conveyor path 5 in which the magnetic card 4 is conveyed, and a sensor 11 connected to a sensor circuit 12 is arranged in the card conveyor path 5 near the recording head 1. When the sensor circuit 12 receives a signal indicating that the sensor 11 detects the magnetic card 4, a detection output from the sensor circuit 12 is supplied to a CPU (Central Processing Unit) 10 and one input terminal of an AND circuit 13. On the other hand, when the CPU 10 receives the detection output of the magnetic card 4 from the sensor circuit 12, the CPU 10 drives a drive circuit 14 to cause the recording head 1 to write data on the magnetic card 4.
In this case, the CPU 10 supplies the write data to the other input terminal of the AND circuit 13 on the basis of a write clock generated by an output from an encoder (not shown) operated in synchronism with the convey speed of the magnetic card 4. In the AND circuit 13, the logical product between the detection output of the magnetic card 4 from the sensor circuit 12 and the write data from the CPU 10 is calculated, and the logical product output is supplied to the drive circuit 14 to energize the winding coil 1b of the recording head 1. As a result, the data is written on a magnetic track of the magnetic card 4.
In the conventional data write apparatus, when the magnetic card 4 is detected by the sensor 11, the AND circuit 13 supplies the write data from the CPU 10 to the drive circuit 14, thereby energizing the recording head 1. A current caused to flow into the winding coil 1b of the recording head 1 is a larger current than 1 A. For this reason, when the magnetic card 4 is jammed in the conveyor path to set a situation wherein the magnetic card 4 is continuously detected for a long time, the winding coil 1b of the recording head 1 is energized at a large current for a long time by the write data from the CPU 10. In this case, the winding coil 1b of the recording head 1 generates heat to melt the coating of the winding coil 1b. As a result, short-circuiting occurs in the coil 1b, so that the recording head 1 becomes disabled.